Intracranial dural arteriovenous fistulae (DAVF) are rare and poorly understood vascular malformations. They consist of a direct connection between arteries and veins, with the nidus located within the dura. DAVFs present as a potentially disabling intracranial hemorrhage in onethird of the patients. Although their pathogenesis is unknown, disordered angiogenesis and thrombosis may have an important role. Several hypotheses will be tested in this project. We will determine whether the presence of cortical venous drainage is a predictor of intracranial hemorrhage (ICH). Further, we will test whether low natural history risk patients have a better outcome after attempted therapy. To assess possible causal factors, we will test whether pro-thrombotic genetic polymorphisms and oral contraceptive use are associated with the occurrence of DAVF. The Specific Aims will be as follows: 1) To determine clinical characteristics of DAVF patients who present with ICH, 2) to document the treatment response and longterm outcome in DAVF patients, 3) to determine the frequency of pro-thrombotic genetic polymorphism in DAVF patients compared with controls, and 4) to determine the influence of environmental factors in DAVF formation. This research should provide useful new information about the natural history of DAVF, their optimal management and role of genetic and hormonal factors in their development. In addition the proposed project will combine didactic teaching, mentoring, and clinical research to build upon Dr. Singh's training in neurovascular neurology, thereby allowing her to develop as an independent clinical investigator in neurovascular neurology.